Midline referencing femoral sizing caliper

A method for determining a desirable size of a femoral component of a knee prosthesis for use in locating and securing the knee prosthesis on a distal end of a femur of a patient, said distal femur including an anterior cortex, a distal condyle, and a midline of an anterior-posterior dimension, comprising:

• resecting said distal end of said femur to form a planar surface thereon;
• providing a femoral sizing caliper instrument, the femoral sizing caliper instrument including a caliper body having a posterior paddle thereon, a drill guide body having a midline reference thereon, and a stylus tower having an anterior stylus thereon, the caliper body, the drill guide body and the stylus tower slidably linked to each other whereby when the caliper body and the stylus tower are linearly displaced in reference to the drill guide body, the paddle and the stylus are linearly displaced at an equal rate with respect to the midline reference of the drill guide body;
• placing the drill guide body adjacent said resected distal end of said femur,
• displacing the caliper body and the stylus tower linearly such that the stylus contacts said anterior cortex of said femur and the paddle contacts said posterior condyle of said femur to thereby align the midline reference of the drill guide body with said midline of said anterior-posterior dimension of said distal femur.